Interstellar Skies

The weather is driven by the complex interaction between Earth and the Sun. But it can also be influenced by interstellar space — by “breezes” of particles that blow through the solar system.

These particles are known as cosmic rays. They’re fired through the galaxy by the remnants of exploding stars and other powerful objects. When they hit Earth, they can trigger the formation of clouds and lightning. And if there are enough cosmic rays, they may even transform the planet’s entire climate.

Earth is protected from cosmic rays by three separate shields: the Sun’s magnetic field, Earth’s magnetic field, and Earth’s atmosphere.

The effectiveness of that first line of defense — the Sun’s magnetic field — depends mainly on what surrounds the solar system.

Right now, we’re traveling through a vast “bubble” in space that was cleared out by an exploding star. In this “clear” interstellar environment, the Sun’s magnetic influence extends billions of miles into space.

When the solar system travels through dense interstellar clouds, though, the Sun’s magnetic influence is squeezed inward — in some cases, it extends no farther than Earth. When that happens, our planet is bombarded with more cosmic rays. That not only triggers climate changes, it can also trigger genetic mutations and other effects on life.

So when it comes to life on Earth, it’s best to have clear interstellar skies.

Tomorrow: “rainy” skies.

Script by Damond Benningfield, Copyright 2011

For more skywatching tips, astronomy news, and much more, read StarDate magazine.

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